[请教]BIOS地址映射?

暴雪

原512K的ROM，现换了一个1M的ROM，windows下在 0xFFF0 0000~0xFFF7 FFFF 可以看到追加的512K的内容。
但在启动计算机时(BIOS没有初始化计算机），无法访问追加的512K的ROM。
# R5 C; l8 K) j" P(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)

我的计算机用的是intel的ICH7南桥。
在手册上
$ S0 w, y# [$ ~' G2 R0 c( H: LFWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
FWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
8 O  J! l. i2 F8 o* b3 {The IDSEL programmed in this field addresses the following memory ranges:
% {. `8 j1 K  A: ^& s9 YFF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
3 g, G. L' d# ^. V3 V2 n在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
- H, U6 O8 C6 r3 J6 q7 P(LPC I/F—D31:F0)
2 [8 x$ n  A$ W* ?FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
0 = Disable.
1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
除了上面的数据区域，还有其它的数据区域控制ROM到内存地址的映射吗？

5 j. |  Q% I6 U. g, @2 Z1 p0 V/ Z# e谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
This one clock field is used to indicate which of multiple Firmware components is being selected.
: X6 ]* m2 o. \2 Z+ a; I9 nThe four bits transmitted over AD[3:0] during this clock are compared with values strapped onto
pins on the Firmware component. If there is a match, the Firmware component will continue to
( `9 f1 u- e/ Q/ |7 Edecode the cycle to determine which bytes are requested on a read or which bytes to update on a
write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
: L+ W( T8 k+ ?  L% \- H& K% ?a standby power state.
7 x5 M  B* S" d! D/ h+ X* |
5 _" C: O) L5 [: x' X详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf
$ ], J3 n) o; _, `' d
1 c1 B" F* |8 o8 U在ICH 7 中似乎就这几个吧(FWH_SEL1,FWH_SEL2,FWH_DEC_EN1,BIOS_CNTL),据我现在知道的.